Conventionally, as a calibration system of this kind, as shown in, for example, Patent Literature 1, there is disclosed a calibration system configured so that gas is allowed to flow from a gas cylinder disposed on an electronic balance to fluid control equipment and, for example, a fluid control valve provided in the fluid control equipment is calibrated so that the gas flow rate outputted from the fluid control equipment at this time is matched with a gas flow rate allowed to flow from the cylinder to the fluid control equipment.
More specifically, this calibration system is configured so that, by utilizing the fact that a measurement value of an electronic balance is varied with consumption of gas in the cylinder, a gas flow rate flowing from the cylinder to the fluid control equipment is calculated based on a variation amount of this measurement value.
However, in practice, a pressure inside the cylinder is reduced with consumption of the gas and a temperature of the gas inside the cylinder and a temperature of the cylinder per se are varied, which results in that convection occurs around the cylinder and water droplets are adhered on a surface of the cylinder.
Therefore, the measurement value of the electronic balance becomes a value including an influence of the convection or the water droplets mentioned above, and it is difficult to accurately calculate a gas flow rate flowing from the cylinder to the fluid control equipment based on the variation amount of this measurement value, and there arises a problem that the fluid control equipment cannot be calibrated with accuracy.